The invention relates to a transformer, comprising a core of a soft-magnetic material provided with a first winding and a second winding which is coupled thereto, each winding consisting of at least one wire-shaped conductor.
An example of such a transformer is known from PIRE 47 No. 8 (August 1959), pp. 1337-1342. In many cases it is desirable to minimize the leakage inductance of the transformer, i.e. the coupling between the windings is as high as possible. This requirement must be satisfied over a wide frequency range if the transformer is to be used in a system having a large bandwidth. The cited publication describes steps for increasing the coupling, for example the twisting of the conductors constituting the windings. Furthermore, the use of a toroidal transformer core may also contribute to increased coupling. In practice, however, it has been found that total coupling of the windings cannot be adequately approached, so that some leakage inductance is inevitable.